They're everywhere. Stalking you, monitoring you. Tracking your online activity to see if you want, say, a once-in-a-lifetime deal on the latest best selling audiobook. You undoubtedly don't, but it won't stop the ad from harassing you at every new tab.
Now imagine, perhaps using some kind of Minority Report-style future tech, if those ads came offline into the physical world and stalked you and stalked you until, who knows, you bought some cheap Egyptian cotton sheets you didn't need. Or maybe some protein shake you'll never use. The horror.
That's exactly what comedy writers Pocketwatch propose in this funny mock trailer called Stalked by an Ad, where a group of friends are relentlessly pursued IRL by online ads. "They know when you bought cat food, they know when you bought binders, don't fight them, you can't win!" Terrifying.